Ruptured internal carotid artery bifurcation aneurysm presenting with only intracerebral hemorrhage without subarachnoid hemorrhage--case report.

A 55-year-old man presented with intracerebral hemorrhage (ICH) without subarachnoid hemorrhage (SAH) manifesting as acute onset of consciousness disturbance and right hemiparesis. Computed tomography showed ICH mainly localized in the left putamen, but no evidence of SAH. Magnetic resonance angiography demonstrated a cerebral aneurysm originating from the bifurcation of the left internal carotid artery, which was considered to be responsible for the ICH. The patient underwent emergent intravascular surgery for coil embolization of the aneurysm, and his neurological symptoms gradually recovered with rehabilitation after surgery. Although ICH without SAH is a rare presentation of cerebral aneurysm, ruptured cerebral aneurysm should be considered as a potential cause of ICH. The localization and extent of ICH may be suggestive of latent cerebral aneurysm in such cases.